But I've heard this story from three separate people at different times, so I believe it's true.
A man starts a job at a large crisp manufacturer in the UK. Let's call them Strollers. At the time (I don't know if they still do it, because of this) all new recruits in the head office were sent to one of the manufacturing sites to see how the products were made, and what their core business was about.
They're taken through the site induction, given security passes etc, then given a tour of the offices, where they meet and greet all the local staff, before suffering a morning full of the usual corporate nonsense and lectures. Then, just before lunch, they're told that they're visiting the plant.
So they get kitted out in the relevant PPE, and *stroll* into the building. As they go in the entrance, someone in a hi-vis waistcoat explains the safety procedures, and what happens if the fire alarm sounds.
Tired after a morning full of someone else talking, and no doubt looking forward to lunch, our hero gazes off into the distance and stops listening. Somewhere along the line, he hears the words "Press the red button". Looking to his left, he sees such a red button. Pointing to it, he asks "Like this one?"
"Yes" comes the reply.
He pushes the button. There's the slow inevitable sounds of EVERYTHING turning off. Fans stop whirring, conveyor belts stop moving, ovens stop baking etc...
Then there's uncomfortable silence.
"Why did you press that?"
"Because you told me to."
"I said, 'If there's an emergency, press the red button'"...
Yes, our hero shut down *Strollers* Crisps manufacturing plant for a couple of days, as once the machines are down, everything has to be drained, cleaned, and made ready to start up again.
*names changed to protect the guilty